System and method for controlling output-timing parameters of power converters

ABSTRACT

A system and method is provided for utilizing output-timing data to control at least one output timing parameter of a point-of-load (“POL”) regulator. Specifically, a power supply controller (“controller”) is adapted to transmit output-timing data to at least one POL regulator. In one embodiment of the present invention, each POL regulator includes an output builder, a control unit and a storage device. The control unit is adapted to store the output-timing data in the storage device. The control unit and the output builder are then adapted to produce an output having at least one output timing parameter in accordance with the output-timing data. Examples of output-timing data include sequencing data, turn-on data, turn-off data, termination data, slew-rate data, etc. For example, a POL regulator may be adapted to utilize output-timing data, or a portion thereof (e.g., slew-rate data), to generate an output having a particular slew rate. Similarly, a POL regulator may be adapted to utilize output-timing data, or a portion thereof (e.g., sequencing data, turn-on data, etc.), to determine (or calculate) a period of time to wait (e.g., delay period) before the output is generated. In other words, output-timing data can be used to produce a series of outputs in a particular order, or sequence.

RELATED APPLICATION DATA

This patent application is a continuation of U.S. patent applicationSer. No. 10/388,831, for SYSTEM AND METHOD FOR CONTROLLING OUTPUT-TIMINGPARAMETERS OF POWER CONVERTERS, filed Mar. 14, 2003, now issued as U.S.Pat. No. 6,936,999 on Aug. 30, 2005.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to controlling a point-of-load (“POL”)regulator output, or more particularly, to a system and method ofutilizing output-timing data to control at least one output timingparameter of a POL regulator.

2. Description of Related Art

Point-of-load (“POL”) regulators, which are also referred to as voltageregulators or DC/DC converters, are commonly used in conjunction withelectronic circuits. This is because the voltage/current requirements ofelectronic circuits typically differ from the voltage that is readilyavailable or the current that can practically be delivered. For example,some electronic devices only include a single voltage input (e.g., 12v),but require different voltages for circuits contained within (e.g., 3v,5v, 9v, etc.). A common solution is to design multiple POL regulatorswithin the device for converting the single input voltage into multiplevoltage levels.

Similarly, some electronic devices include circuits that require lowvoltage (e.g., 1v), high current (e.g., 100 A) power supplies. This isproblematic in that it is impractical to deliver high current at lowvoltage levels over a relatively long distance and still meet desiredregulation performances. A common solution is to use a high voltage, lowcurrent power supply and design a POL regulator near the internalcircuit. This allows low current to travel throughout the device, andprovides a low voltage, high current power supply (i.e., using the POLregulator) near the internal circuit.

Traditionally, POL regulators operate in conjunction with at least onepower supply controller. The controller (1) activates and partiallyprograms the POL regulator by providing data directly to the POLregulator, (2) monitors the output of the POL regulator by measuringdata external to the POL regulator, and (3) allows the output of the POLregulator to be transmitted to an external load circuit by controllingan external switch. Specifically, the controller provides the POLregulator with output-voltage-set-point data and enable data. The POLregulator, in response to receiving the enable data, produces an outputhaving a voltage level in accordance with the output-voltage-set-pointdata. The output of the POL regulator is then measured by thecontroller. If the output is correct, the controller activates anexternal transistor switch, which allows the output to be transmitted tothe external load circuit. If a particular output slew rate is required,the controller can toggle or control linearly the external transistorswitch to achieve the desired slew rate. Thus, the power supplycontroller controls the output timing parameters of each POL regulator(e.g., sequencing, slew rate, etc.) by controlling a plurality ofexternal transistor switches.

The drawback with such a control system is that it adds complexity,expense and size to the control system by requiring the controller tocommunicate with multiple devices (e.g., a POL regulator and an externaltransistor switch) to control the output timing parameters of a singlePOL regulator. Thus, it would be advantageous to have a system andmethod of controlling the output timing parameters of a POL regulatorthat overcomes these drawbacks.

SUMMARY OF THE INVENTION

The present invention provides a system and method of utilizingoutput-timing data to control at least one output timing parameter of apoint-of-load (“POL”) regulator. Embodiments of the present inventionoperate in accordance with a power supply controller (“controller”) andat least one POL regulator. Specifically, in one embodiment of thepresent invention, each POL regulator includes an output builder, acontrol unit and a storage device. In this embodiment, the controller isadapted to transmit output-timing data to the regulator via a bus, ormore particularly to the control unit (e.g., microprocessor, etc.)located within the POL regulator. The output-timing data is then storedin the storage device and used by the control unit and the outputbuilder (e.g., voltage generating device, etc.) to produce an output.

Specifically, POL regulators are traditionally adapted to receivevoltage set-point data and produce an output having a voltage level inaccordance with the voltage set-point data. In a preferred embodiment ofthe present invention, the POL regulator is further adapted to receiveoutput-timing data and utilize the output-timing data to determine atleast one output timing parameter. Examples of output timing parametersinclude when to generate the output (e.g., sequencing data, turn-ondata), when to stop generating the output (e.g., termination data,turn-off data), the slew rate of the output (e.g., slew-rate data), etc.For example, a POL regulator operating in accordance with one embodimentof the present invention may utilize the output-timing data, or aportion thereof (e.g., slew-rate data), to generate an output having aparticular slew rate. Similarly, a POL regulator operating in accordancewith one embodiment of the present invention may utilize theoutput-timing data, or a portion thereof (e.g., sequencing data, turn-ondata), to determine (or calculate) a period of time to wait (e.g., delayperiod) before the output is generated. In other words, at least aportion of the output-timing data can be used to generate a series ofoutputs in a particular order, or sequence. For example, a first POLregulator may produce a one volt output ten milliseconds after an eventhas occurred (e.g., activation data has been received, etc.), a secondPOL regulator may produce a five volt output two milliseconds after theevent has occurred, etc.

A more complete understanding of the system and method of utilizingoutput-timing data to control at least one output timing parameter of aPOL regulator will be afforded to those skilled in the art, as well as arealization of additional advantages and objects thereof, by aconsideration of the following detailed description of the preferredembodiment. Reference will be made to the appended sheets of drawingswhich will first be described briefly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a prior art POL or DC/DC control system.

FIG. 2 depicts a POL control system operating in accordance with oneembodiment of the present invention.

FIG. 3 depicts a POL regulator operating in accordance with oneembodiment of the present invention.

FIG. 4 illustrates one method of communicating with a POL regulator overa serial bus.

FIG. 5 illustrates one communication cycle that may be transmittedto/from a POL regulator.

FIG. 6 is a flow chart depicting one method of utilizing output-timingdata in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention provides a system and method of utilizingoutput-timing data to control at least one output timing parameter of aPOL regulator. In the detailed description that follows, like elementnumerals are used to describe like elements illustrated in one or morefigures.

FIG. 1 illustrates a prior art DC/DC control system 10 where the powersupply controller (“controller”) 110 communicates with a plurality ofDC/DC converters (i.e., 120, 130 and 140), also referred to as voltageregulators or POL regulators, via a plurality of six bit parallel buses(i.e., 112, 114 and 116), and a plurality of external circuits (e.g.,R1/S1, R2/S2, R3/S3) via a plurality of three-wire output connections(i.e., 122–126, 132–136, and 142–146). More particularly, each six bitparallel bus includes an enable/disable bit and five VID code bits, andeach three-wire output connection includes a voltage monitoring line(i.e., 122, 132 and 142), a current monitoring line (i.e., 124, 134 and144), and a switch enable line (i.e., 126, 136, 146).

As shown in FIG. 1, the controller 110 controls the output voltage ofeach DC/DC converter by activating and partially programming theconverter via the six bit parallel bus, and monitoring the converter viathe three-wire output connection. For example, the controller 110provides output-voltage-set-point data to the DC/DC converter 140 viathe VID code portion of the six bit parallel bus 116. The controller 110then activates the DC/DC converter 140 via the enable/disable portion ofthe six bit parallel bus 116. Once activated, and in accordance with theoutput-voltage-set-point data, the DC/DC converter 140 converts thevoltage provided via the power supply 100 (e.g., 48v) into an outputvoltage V_(A). The controller 110 then verifies that the output voltageV_(A) is the desired voltage by measuring the voltage via the voltagemonitoring line 142. If the output voltage V_(A) is acceptable, it isprovided to the load (not shown) by activating the transistor switch S₁via the switch enable line 146. The controller 110 can then continuouslymonitor the output voltage and the output current by measuring thevoltage via the voltage monitoring line 142 and measuring the voltagedrop across the sense resistor R₁ (i.e., the voltage differentialbetween the current monitoring line 144 and the voltage monitoring line142), respectively. If a particular slew rate is required, thecontroller 110 can toggle or control linearly the transistor switch S₁via the switch enable line 146 to produce the desired slew rate. Thecontroller 110 communicates (i.e., partially programs, activates,monitors, and controls the output) with the remaining DC/DC converters120, 130 in the same manner.

The problem with such a control system 10 is that it adds complexity,expense and size to the overall electronic device (not shown) byrequiring the controller 110 to communicate with multiple devices inorder to control the output of a DC/DC converter (e.g., 140). Forexample, in order to generate and provide an output voltage to anexternal load circuit, the controller must communicate with the DC/DCconverter (to produce a particular output voltage) and the externaltransistor switch (to allow the output voltage to be provided to theexternal load circuit). Not only does such a system require severalexternal circuits (e.g., external transistor switches), but it alsorequires additional wires (or traces) in order to communicate with theexternal circuits.

FIG. 2 illustrates a POL control system 20 operating in accordance withone embodiment of the present invention. Specifically, a controller 210is used to communicate with a plurality of POL regulators (i.e., 220,230, 240 and 250) via a bus 200. In one embodiment of the presentinvention, this communication includes providing voltage set-point dataand enable data to each POL regulator. The data is then used by each POLregulator to convert the input voltage (i.e., V_(IN)) provided via thepower bus 260 into an output voltage. Specifically, after each POLregulator has been activated (i.e., receives enable data), it producesan output having a voltage level in accordance with the voltageset-point data. For example, if the voltage set-point data correspondsto one volt, then the POL regulator will produce a one volt output. Itshould be appreciated that the POL regulators depicted herein (e.g.,220, etc) include, but are not limited to, point-of-load regulators,power-on-load regulators, DC/DC converters, voltage regulators, and allother programmable voltage or current regulating devices (including allsingle and multiple output devices) generally known to those skilled inthe art. It should further be appreciated that the controller (e.g.,210) may exist as a stand-alone device (as depicted in FIG. 2) orintegrated into another device, such as a front-end converter (notshown) or another POL regulator.

In a preferred embodiment of the present invention, the controller 210is further adapted to identify at least one output timing parameter of aPOL regulator by transmitting output-timing data to the POL regulator.For example, in response to being activated (i.e., receiving enabledata), a POL regulator may generate an output having a particular slewrate in accordance with at least a portion of the output-timing data,(e.g., slew-rate data). Similarly, after being activated, a POLregulator may wait a period of time before generating an output—wherethe period of time either corresponds to at least a portion of theoutput-timing data (e.g., sequencing data) or is calculated using atleast a portion of the output-timing data (e.g., turn-on data). In otherwords, the delay period can either be provided by the controller 210(e.g., sequencing data) or calculated using data that has been providedby the controller 210 (e.g., turn-on data).

For example, a POL regulator might generate a one volt output fivemilliseconds after receiving activation data if it received voltageset-point data and sequencing data corresponding to one volt and fivemilliseconds, respectively. Alternatively, a POL regulator mightgenerate a one volt output one millisecond after receiving activationdata if it received voltage set-point data, slew-rate data and turn-ondata corresponding to two volts, one volt per millisecond and threemilliseconds, respectively. This is because it takes two milliseconds toproduce a two volt output at a slew rate of one volt per millisecond. Inother words, a one millisecond delay period plus a two millisecondvoltage ramp-up period equals three milliseconds (e.g., turn-on data).It should be appreciated, however, that the time measurements discussedherein are not limited to measurements taken from (or even used inconjunction with) the reception of enable or activation data. Thus, timemeasurements taken from any known event (e.g., the reception of aparticular transmission cycle or data bit, the occurrence of aparticular condition, etc.) are within the spirit and scope of thepresent invention. It should further be appreciated that the termsgenerated and produced as used herein are used to indicate apoint-in-time (approximately) when an output is being provided by thePOL (e.g., to an external load), regardless of whether the output is atits peak voltage or ramping up to its peak voltage. Thus, an output offive volts is being generated or produced at the time it is beingprovided by (or delivered external to) the POL, regardless of whetherthe output is five volts at the time it's initially provided or rampingup to five volts. It should also be appreciated that the output timingparameters associated with the output-timing data, and therefore theoutput-timing data itself, are not limited to slew rate, sequencing orturn-on parameters, but further include all other output timingparameters generally known to those skilled in the art. Thus, forexample, output-timing data may be used to determine when a POLregulator is to turn-off its output (e.g., termination data or turn-offdata).

In one embodiment of the present invention, as shown in FIG. 3, each POLregulator 300 includes an output builder 310, a point-on-load controlunit 320 (“POL control unit”) and a storage device 330. It should beappreciated that the output builder 310 includes, but is not limited to,all voltage building and converting circuits generally known to thoseskilled, including circuits that are single and multi-staged (e.g.,circuits that include a digital to analog converter, a pulse widthmodulation controller, an analog voltage reference circuit, etc.). Itshould further be appreciated that the POL control unit 320 includes,but is not limited to, application specific integrated circuits (ASICs),processors, microprocessors, programmable devices and all othercomputing devices generally known to those skilled in the art. It shouldalso be appreciated that the storage device 330 can be a long term orshort term storage device, including, but not limited to, registers,RAM, ROM, EPROM, EEPROM, flash memory, and all other digital datastorage devices generally known to those skilled in the art.

Referring to FIG. 3, the POL control unit 320 is adapted to receiveoutput-timing data and store the output-timing data in the storagedevice 330. For example, if the storage device 330 is a plurality ofregisters, the output-timing data may be stored in at least oneoutput-timing register (e.g., a sequencing register, a slew-rateregister, etc.). This data is then used by the control unit 320 (or tosome degree the output builder 310) to generate an output. Specifically,the output builder 310 is adapted to generate an output in accordancewith data received/stored by the control unit 320 (e.g., voltageset-point data, output-timing data, etc.). For example, in accordancewith one embodiment of the present invention, the output builder 310 andthe control unit 320 are adapted to generate an output that includes aparticular slew rate, or an output that is to be produced at aparticular time, etc.—depending upon the type of output-timing datareceived/stored. It should be appreciated that the location, type,and/or number of components illustrated in FIG. 3 are merely toexemplify the environment in which the present invention operates, andshould not be considered limitations of the present invention. Forexample, a POL regulator including more than one output builder, havingcomponents in different locations (e.g., a storage device within the POLcontrol unit, a storage device external to the POL regulator, etc.), orhaving additional (or fewer) components is within the spirit and scopeof the present invention.

While the output-timing data can be transmitted via a parallel bus, oneembodiment of the present invention involves transmitting theoutput-timing data over a bi-directional serial data bus (eithersynchronously or asynchronous) (see e.g., FIG. 2, bus 200). In otherwords, the bi-directional serial bus is either a two-wire serial databus (e.g., I²C) that allows data to be transmitted asynchronously or asingle-wire serial data bus that allows data to be transmittedsynchronously (i.e., synchronized to a clock signal). In anotherembodiment of the present invention the serial data bus (or a portionthereof) is superimposed over (or coexistent with) a power bus used todeliver power from the front-end converter to the POL regulators (seee.g., FIG. 2, power bus 260).

FIG. 4 illustrates one method of communicating over a single-wire serialbus. Specifically, a transmission line 40 is created by propagating aclock signal 400 over the serial bus. The clock signal 400 can begenerated by the controller, a particular POL regulator (e.g., the POLregulator with the least significant address), or an external device.The clock signal 400 synchronizes the various communicating devices(i.e., the POL regulators and the controller) and creates a series ofclock cycles 410, each one including a data bit 420. This allows thevarious communicating devices to transmit a single bit of data for everyclock cycle 410. In other words, each communicating device transmitsdata by leaving/pulling the data bit 420 high or low (i.e., binary oneor zero). It should be appreciated that FIG. 4, as discussed herein, isnot intended to limit the present invention, but to provide an exampleas to how communication can occur over a single-wire serial bus.

FIG. 5 illustrates one method of transmitting information between thecontroller and at least one POL regulator. Specifically, a forty-two bitcommunication cycle 50 can be used to transmit output-timing data,voltage set-point data, and/or enable data. As shown in FIG. 5, theforty-two bit transmission cycle 50 includes a four bit start sequence510, a sixteen bit (with parity) address set 520, an eight bit (withparity) command set 530, a first acknowledgement bit 540, an eight bit(with parity) data set 560, and a second acknowledge bit 570. Anadditional bit 550 has been added to ensure that the command set 540 isexecuted before the data set 560 is provided. It should be appreciatedthat the communication cycle 50 depicted in FIG. 5 is not intended tolimit the present invention, but to illustrate how information can betransmitted over a serial bus. Therefore, communication cyclescontaining more or less information and/or bits is within the spirit andscope of the present invention.

The first and second acknowledgement bits 540, 570 are used toacknowledge the reception of the command set 530 and the data set 560,respectively. It should be appreciated that the device responsible forproviding the first and second acknowledgement bits 540, 570 variesdepending upon whether the information is being sent to or from the POLregulator (i.e., whether the information is being written, read, orprovided).

The command set 530, data set 560, and address set 520 enable thecontroller and the POL regulators to write, read and provide data.Specifically, (i) the command set 530 is used to identify whether andwhat the controller is writing (e.g., writing to the output-timingregister), the controller is reading (e.g., reading the statusregister), or the POL regulator is providing (e.g., providingoutput-timing data), (ii) the address set 520 is used to identify thePOL regulator(s) that is being written to or read, or the POL regulatorthat is providing information, and (iii) the data set 560 is used toidentify the actual data that is being written, read, or provided.

The start sequence 510 and address set 520 are used, in part, toidentify the sender of the information. For example, the controller usesa different start sequence 510 than the POL regulators. Thus, thecontroller can determine, by reading the start sequence 510 of thecommunication cycle 50 being transmitted, whether a POL regulator isalso attempting to send a communication cycle 50 at the same time.Similarly, each POL regulator has a different address set 520. Thus, aPOL regulator can determine, by reading the start sequence 510 andaddress set 520 of the communication cycle 50 being transmitted, whetheranother POL regulator or the controller is also attempting to send acommunication cycle 50 at the same time. If multiple devices areattempting to send a communication cycle 50, bus-arbitration data isused to allocate or arbitrate bus use. It should be appreciated that thebus-arbitration data can either be stored (or hard wired) as a defaultvalue or provided by the power supply controller and stored in the POLstorage device.

One method of utilizing output-timing data to determine at least oneoutput timing parameter is illustrated in FIG. 6. Specifically, at step600, the POL control unit receives output-timing data, which may includeslew-rate data, sequencing data, termination data, etc. Theoutput-timing data is then stored in the POL storage device at step 620.For example, if the POL storage device is a plurality of registers, thenthe output-timing data (e.g., slew-rate data, sequencing data, etc.) maybe stored in at least one of the plurality of registers (e.g., aslew-rate register, a sequencing register, etc.). At step 640, the POLcontrol unit receives enable data, which activates the POL regulator forthe production of an output. At step 660, the POL control unit uses theoutput-timing data stored in the POL storage device to determine atleast one output timing parameter. It should be appreciated, however,that step 660 may be (at least in part) more applicable during certaintime periods, depending on the nature of the output-timing data. Forexample, if the output-timing data is related to the time in which theoutput is to be generated or the slew rate of the output, step 660 maybe more applicable to producing the output. Alternatively, if, forexample, the output-timing data is related to the time in which theoutput is to be terminated, step 660 may be more applicable after theoutput has been produced.

Having thus described a preferred embodiment of a system and method ofutilizing output-timing data to control at least one output timingparameter of a point-of-load regulator, it should be apparent to thoseskilled in the art that certain advantages of the system have beenachieved. It should also be appreciated that various modifications,adaptations, and alternative embodiments thereof may be made within thescope and spirit of the present invention. The invention is furtherdefined by the following claims.

1. A power control system comprising: a power controller adapted toprovide output voltage control signals; a serial data bus operativelyconnected to the power supply controller; and at least one voltageregulator operatively connected to the data bus and receiving the outputvoltage control signals via the data bus, the at least one voltageregulator including a control unit adapted to control operation of thepower conversion circuit responsive to the output voltage controlsignals; wherein the output voltage control signals further comprise atleast one command setting the output voltage to a desired value.
 2. Apower control system comprising: a power controller adapted to provideoutput voltage control signals; a serial data bus operatively connectedto the power supply controller; and at least one voltage regulatoroperatively connected to the data bus and receiving the output voltagecontrol signals via the data bus, the at least one voltage regulatorincluding a control unit adapted to control operation of the powerconversion circuit responsive to the output voltage control signals;wherein the output voltage control signals further comprise at least onecommand setting a rate of change of the output voltage to a desiredvalue.
 3. A power control system comprising: a power controller adaptedto provide output voltage control signals; a serial data bus operativelyconnected to the power supply controller; and at least one voltageregulator operatively connected to the data bus and receiving the outputvoltage control signals via the data bus, the at least one voltageregulator including a control unit adapted to control operation of thepower conversion circuit responsive to the output voltage controlsignals; wherein the output voltage control signals further comprise atleast one command setting a turn-on delay of the output voltage.
 4. Apower control system comprising: a power controller adapted to provideoutput voltage control signals; a serial data bus operatively connectedto the power supply controller; and at least one voltage regulatoroperatively connected to the data bus and receiving the output voltagecontrol signals via the data bus, the at least one voltage regulatorincluding a control unit adapted to control operation of the powerconversion circuit responsive to the output voltage control signals;wherein the output voltage control signals further comprise at least onecommand setting a turn-off delay of the output voltage.
 5. A powercontrol system comprising: a power controller adapted to provide outputvoltage control signals; a serial data bus operatively connected to thepower supply controller; and at least one voltage regulator operativelyconnected to the data bus and receiving the output voltage controlsignals via the data bus, the at least one voltage regulator including acontrol unit adapted to control operation of the power conversioncircuit responsive to the output voltage control signals; wherein theoutput voltage control signals further comprise at least one multi-bitcommand message.
 6. The power control system of claim 5, wherein themulti-bit command message includes at least an address of the at leastone voltage regulator.
 7. A power control system comprising: a powercontroller adapted to provide output voltage control signals; a serialdata bus operatively connected to the power supply controller; and atleast one voltage regulator operatively connected to the data bus andreceiving the output voltage control signals via the data bus, the atleast one voltage regulator including a control unit adapted to controloperation of the power conversion circuit responsive to the outputvoltage control signals; wherein the at least one voltage regulatorfurther comprises a plurality of voltage regulators, the output voltagecontrol signals being directed to plural ones of the plurality ofvoltage regulators.
 8. A power control system comprising: a powercontroller adapted to provide output voltage control signals; a serialdata bus operatively connected to the power supply controller; and atleast one voltage regulator operatively connected to the data bus andreceiving the output voltage control signals via the data bus, the atleast one voltage regulator including a control unit adapted to controloperation of the power conversion circuit responsive to the outputvoltage control signals; wherein the control unit further comprises amemory adapted to store the output voltage control signals received fromthe power controller.
 9. The power control system of claim 8, whereinthe control unit is further adapted to control operation of the powerconversion circuit responsive to the output voltage control signalsstored in the memory.
 10. The power control system of claim 8, whereinthe output voltage control signals further comprise at least one commandsetting the output voltage to a desired value, the control unit therebycontrolling operation of the power conversion circuit to provide theoutput voltage at the desired value and having a slew rate defined bypreviously stored control signals.
 11. A method of regulating an outputvoltage comprising: receiving output voltage control signals from acontroller via a serial bus; storing the output voltage control signalsin a memory; and generating an output voltage responsive to the storedoutput voltage control signals; wherein the step of receiving outputvoltage control signals further comprises receiving at least one commandsetting the output voltage to a desired value, and the step ofgenerating an output voltage further comprises generating the outputvoltage at the desired value.
 12. A method of regulating an outputvoltage comprising: receiving output voltage control signals from acontroller via a serial bus; storing the output voltage control signalsin a memory: and generating an output voltage responsive to the storedoutput voltage control signals; wherein the step of receiving outputvoltage control signals further comprises receiving at least one commandsetting a rate of change of the output voltage to a desired value, andthe step of generating an output voltage further comprises generatingthe output voltage with the rate of change at the desired value.
 13. Amethod of regulating an output voltage comprising: receiving outputvoltage control signals from a controller via a serial bus; storing theoutput voltage control signals in a memory; and generating an outputvoltage responsive to the stored output voltage control signals; whereinthe step of receiving output voltage control signals further comprisesreceiving at least one command setting a desired turn-on delay of theoutput voltage, and the step of generating an output voltage furthercomprises generating the output voltage in accordance with the desiredturn-on delay.
 14. A method of regulating an output voltage comprising:receiving output voltage control signals from a controller via a serialbus; storing the output voltage control signals in a memory; andgenerating an output voltage responsive to the stored output voltagecontrol signals; wherein the step of receiving output voltage controlsignals further comprises receiving at least one command setting adesired turn-off delay of the output voltage, and the step of generatingan output voltage further comprises generating the output voltage inaccordance with the desired turn-off delay.
 15. A method of regulatingan output voltage comprising: receiving output voltage control signalsfrom a controller via a serial bus; storing the output voltage controlsignals in a memory; and generating an output voltage responsive to thestored output voltage control signals; wherein the step of receivingoutput voltage control signals further comprises receiving a multi-bitcommand message.
 16. The method of claim 15, wherein the step ofreceiving a multi-bit command message further comprises receiving anaddress.
 17. A voltage regulator comprising: a serial data businterface; a memory adapted to store control data received externallyvia the serial data bus interface; a voltage control unit adapted tocalculate at least one parameter of an output voltage based on saidcontrol data; and a voltage conversion circuit adapted to generate theoutput voltage in accordance with the at least one parameter.
 18. Thevoltage regulator of claim 17, wherein the control data furthercomprises slew-rate data and the voltage control unit is further adaptedto determine a slew rate for the output voltage determined in accordancewith the slew-rate data.
 19. The voltage regulator of claim 17, whereinthe control data further comprises turn-off data and the voltage controlunit is further adapted to determine a turn-off period of time that isto be waited before the voltage control unit terminates the outputvoltage.
 20. The voltage regulator of claim 17, wherein the control datafurther comprises turn-on data and the voltage control unit is furtheradapted to determine a turn-on period of time that is to be waitedbefore the voltage control unit activates the output voltage.
 21. Thevoltage regulator of claim 17, wherein the memory further comprises atleast one register.
 22. The voltage regulator of claim 17, wherein thevoltage control unit is adapted to control operation of the powerconversion circuit to provide the output voltage at a desired valuedefined by received control data and having a slew rate defined bypreviously stored control data.